Piston-ring mold



ATTORNEY.

S.M.UDALE PISTON RING MOLD Filed March 14, 1923 Aug. 25, 1925.

/ZAAAAAAA/ /ooooeoaa/ Patented Aug. 25, 1.925.

UNITED STATES sTANLE'rM. UnALEjor DETROIT, MICHIGAN, AssIGNoa To Y nn'rnon, MICHIGAN.

EARL HOLLEY, 0F

, rIs'roN-nINe Mom).

Application led March 14, 1923. Serial No. 625,070.

T 0` all whom t majz/ concern:

Be it known that I, STANLEY M. Ulmen, a citizen of the United Sta-tes, residing at 893 Lothrop Ave., Detroit, in the county of Tay/ne and State of Michigan, have invented certain new and useful Improvements in Piston-Ring Molds, of which the following is a specification.

This invention relates to piston ring molds and specifically to an improved mold and core adapted to produce cast rings at a minimum cost and of uniform quality.

In the manufacture of cast iron piston rings it is extremely desirable to obtain the finest possible granulation of the graphitic carbon combined with. uniformity of distribution. The .co-efficient of friction, resistance to wear, elasticity and resistance to shock are all factors which render piston rings suitable for the severe uses to which they are putin internal combustion engines and the like, and these factors are determined by the uniform distribution of the graphitic carbon.

The figure shows in cross sectional elevation the mold with core and rings in place.

The mold consists of two matching'hollow molds A and B inclosingl a baked dry sand core C which may be provided with aA central conical sprue or entrance D. A plurality of horizontal gates E radiate from this central sprue D to each of the grooves F in the core C. These grooves F are uniformly spaced in the circumference of the core C, except in the middle where a gap G is left.

In the middle of the core C a pair of knock-outs H and J are provided which contact with the core at the gap G referred to. The outside surface of the dry sand core C, against which the piston rings are cast in the grooves F, is protected by a coating preferably of magnesium oxide, as set forth in the copcnding application of D. H. Meloche, Serial No. 548,475, filed 31 March 1925.2. The powdered magnesium oxide is mixed with water and is applied with a brush or airspray, gluten being used as a binder and is dissolved in the Water for that puy ose. The core is of course dried after being coated. This coating prevents sand being carried by the iron into the v grooves where it would interfere with the subsequent machining.

The partlcular coating which has been found best for lining the iron lmolds has been found to be powered fire clay suspended in water in which water glass is gust1922. The finely ground fire clay is y mixed with an equal Weight of a 10%` Solution of sodium silicate in water. This mixture is applied with a paint brush or air spray onto the heated surface of the mold, which is repeatedly heated during the painting operationso as to render the coating adherent. v A thick pulverent coating of '.,lampblack 1s super-imposed on the coating of. soluble silicate as described in theco-pending application of D. H. Meloche, Serial No. 57 9,- 927, filed 5 August 1922. l

The molds are heated to between 650 and 11.50 F. before the iron is poured in, the iron being considerably above 2200 I". The casting is ejected whilst it is still above its critical temperature at 14500 F. The iron poured consists of a mixture suitable for piston rings, that is to say it consists of #l foundry pig mixed with a small per centage (10%) of high grade low carbon steel scrap. The silicon content is -sutliciently high (2.25%) to ensure that the major portion of the carbon content is instantaneously precipitated and `uniformly distributed as fine particles of graphitic carbon throughout the ferrite mass.

The above process corresponds to that described in the application to D. H. Meloche, Serial No. 622,675, filed 3 March, 1923, and the product corresponds to the application of D. H. Meloche, Serial No. 618,715, filed 12 February 1923, which is acontinuation of Serial No. 559.463,' filed 8 May 1922 by the same inventor.

A strainer core 'K may be placed in the entrance to the sprue D to prevent any dirt being carriedinto the mold.

A conical re-entrant shoulder L is provided in the mold with a corresponding shoulder on the core C to prevent the ferrostatic head ofthe iron within the sprue D causing the core to float up in the mold during the pouring operation.

By providing a plurality of :gates E leading from the sprueD` to the gToovesZF I ensure that the molten iron is fed to each, ring groove simultaneously and at a plu-` susA rality of dil'ercnt, points equally spaced around the circumference and so obtain uniformity throughout each rinfg and flie- 11i-een all the rings.

The refrmftory lire clay coating on the molds A and l5, with the pnlverent coating .of lampblack, render the. annealing ol the 1. A mold adapted for the production of individually cast pistony rings, `comprising a cylindrical core having a vertical axis, a plurality of circumferential grooves in said core, a substatially vertical sprue passage` located in the upper art of said core, a, plurality of gates leading from said sprue lto said grooves, apair of metal molds enclosing said core.

2. A mold adapted for the production of individually cast piston rings,. comprising a cylindrical core havingr a vertical axis, a plurality of circumferential grooves in Said core, a substantially vertical sprue passage located in the upper part of said core, a plurality of gates leading from said sprue to said grooves-ii mold enclosing said core.

In testimony Whereo'lI I affix my signature.

STANLEY M. UDALE. 

